Through dextrous manipulation of the US teen-TV soundtrack market, Imogen Heap has all but supplanted Dido as the favoured voice of emotional turmoil in series like The OC.

But as with Dido, that's a Faustian pact which condemns careers even as it bestows riches beyond imagining. And certainly, one thinks, there ought to be some penalty for anyone prepared to write about the "many windswept yellow stickies of my mind on the molten emotional frontline" or describe how she's "clambering for the scraps and the shatter of us collapsed that cuts me with every could have been", a line I'd be wary of punctuating, let alone singing. Heap's musical style, meanwhile, hasn't progressed too much since 2005's Speak For Yourself, which means that her lyrical gushings are mostly smothered by a dense digital soup of sequenced keyboards, samples and percussion, listening to which is rather like wading through mud. Even when attempting simpler settings, she can't help cluttering them up, fussing over them as if insecure about her basic material: the acappella arrangement of "Earth", for instance, has so many layered vocal counterpoints and beatboxed bass and percussion noises woven into it that the song is effectively stifled. Like the album overall, it's clever but unmoving, an unsatisfactory situation for an art so obsessively concerned with emotion.